混凝土开裂的三维非线性数值模拟

Three-dimensional nonlinear numerical model for concrete fracture analysis

作为一种准脆性材料,混凝土在发生开裂后将表现一定的应变软化特性。该文将Bazant提出的钝断裂带模型,扩展到考虑剪切软化情形,推导出全量算法的三维弥散软化本构关系,并对线性、双线性两种应力应变软化关系采用简化的割线模量折减系数,应用于混凝土开裂扩展的三维数值模拟。通过对比三点弯梁试验的数值模拟结果与试验结果,以及与二维增量关系模型的计算结果进行比较,验证了该模型能较好地模拟混凝土开裂行为。

As a quasi-brittle material, concrete exhibits strain-softening behavior after the formation of micro-cracks. The blunt crack band model proposed by Bazant was used to develop a 3-D softening constitutive relationship for the total magnitude of the yield strees. A simplified method is given for defining the softening factor for linear or bilinear softening. The crack model was implemented in a finite element program and used for 3-D concrete fracture analysis. Numerical simulations of a three-point bending beam compare well with experimental results and with previous numerical results using the 2-D crack model based on the incremental relationship procedure. The results show that the 3-D smeared crack model can provide objective simulation in concrete fracture propagation analysis.